Pontiac Fiero 1988 Service Manual page 559

EGR VALVE I D E N T I F I C A T I O N
O N - C A R S E R V I C E
• Negative backpressure EGR valves will have an
"N" stamped on the top side of the valve after the
part number (Figure C7-3).
• Positive backpressure EGR valves will have a "P"
stamped on the top side of the valve, after the part
number.
• Port EGR valves have no identification stamped
after the part number.
When replacing an EGR valve, always check for
correct part number in the parts catalog or
supplemental bulletin.
1. ASSEMBLY PLANT CODE
2. PART NUMBER
3. DATE BUILT
4. LOOK HERE FOR LETTER:
P = POSITIVE BACK PRESSURE
N = NEGATIVE BACK PRESSURE
BLANK = PORTED VALVE
' 4 S 0 5 3 8 - 6 E
2-27-87
F i g u r e C7-3 - E G R V a l v e I d e n t i f i c a t i o n
R E S U L T S O F I N C O R R E C T O P E R A T I O N
Too much EGR flow (at idle, cruise, or cold
operation) and may result in any of the following
conditions:
• Engine stops after cold start.
• Engine stops at idle after deceleration.
9 Car surges during cruise.
• Rough idle.
Too little or no EGR flow allows combustion
temperatures to get too high during acceleration and
load conditions. This could causes:
• Spark knock (detonation).
• Engine overheating.
• Emission test failure.
DIAGNOSIS
Because the EGR on 2.5L equipped vehicles is not
ECM controlled, a "Scan" tool cannot be used for
diagnosis. Diagnosis of the EGR system on the 2.5 L is
covered in CHART C-7 at the end of this section.
GM
V A L V E
R e m o v e or D i s c o n n e c t
1. Air cleaner.
2. EGR valve vacuum hose at valve.
3. Bolts.
4. EGR valve from manifold.
T]
EGR V A L V E j 3 | B O L T (2) 2 2 N - m (16 FT L B S )
2 I G A S K E T
7S 3184-6E
F i g u r e C7-4 E G R t o M a n i f o l d M o u n t i n g 2.5L
E G R M a n i f o l d P a s s a g e
I n s p e c t
If EGR passages in the inlet manifold indicate
excessive build-up of deposits, the passages should be
cleaned. Care should be taken to ensure that all loose
particles are completely removed to prevent them
from clogging the EGR valve or from being ingested
into the engine.
C l e a n
2.
3.
With a wire wheel, buff the exhaust deposits from
the mounting surface and around the valve.
Look for exhaust deposits in the valve outlet.
Remove deposit build-up with a screwdriver.
Clean mounting surfaces of intake manifold and
valve assemblv.
0
I n s t a l l o r C o n n e c t
1. EGR valve on intake manifold using new gasket.
2. Bolts and tighten to 22 N • m (16 lb. ft.).
3. Vacuum hose to valve.
4. Air cleaner.